This is a Continuation-in-part of U.S. patent application Ser. No. 08/195,952, filed Feb. 11, 1994, now abandoned which is a Continuation-in-part of U.S. patent application Ser. No. 08/100,496, filed Aug. 2, 1993 now abandoned.
We have demonstrated previously that a wild type alternatively spliced p53 (p53as, for alternative splice) RNA exists in cultured cells and normal tissues at approximately 30% of the major p53 RNA form (Han and Kulesz-Martin, Nucleic Acid Res., 20:1979–81, 1992). The predicted protein encoded by the p53as transcript differs from p53 protein in 17 C-terminal amino acids and is truncated by 9 amino acids due to alternative splicing of intron 10 of the wild type p53 gene. Using antibody to the 17 C-terminal amino acids to detect p53as protein, we have demonstrated the following points. p53as protein is an alternatively spliced product of the wild type p53 gene. First detected in mouse epidermal cells, it is present in non-transformed and malignant cells. Like its major counterpart, p53 protein, it is located in the nucleus. However, while p53 antigen activity is primarily found in cells at the G1 stage of the cell cycle and is thought to play a role in G1 arrest in cells following treatment with DNA damaging agents, p53as is found in cells preferentially distributed in the G2 phase of the cell cycle and in a “tail” of cells with >G2 DNA content. These properties of p53as protein were suggestive of cellular functions distinct from the major p53 protein. The well established ability of the p53 protein to oligomerize and our finding of co-expression of p53as antigen activity with p53 in cells suggested potential for cooperation with p53 in its functions related to cell cycle control. This information is described in detail in the original patent application Ser. No. 08/100,496, filed Aug. 2, 1993 which is incorporated herein by reference.
The presence of the p53as protein in tumor cells and antibodies for its detection has applications in basic research on cell growth and differentiation. Presence of a homologous protein in human cells has applications in the diagnosis, prognosis and design of treatment strategy in human diseases of growth and differentiation such as cancer. The association with G2 suggests a functional role in G2 arrest and potential for gene therapy using the p53as coding sequence.